text: 256Background: The TRUMPET registry is a prospective, observational cohort study of patients (pts) with CRPC designed to evaluate treatment patterns and health-related quality of life (HRQoL) outcomes associated with CRPC and its management in a real-world setting. Comorbidities may influence how physicians approach CRPC treatment; therefore, evaluation of comorbidity presence and severity is important. The TIBI-CaP questionnaire measures comorbidity, with the aim of this analysis to validate TIBI-CaP in CRPC. Methods: Data were collected from 302 enrolled CRPC pts treated in academic and community-based sites under routine care. Baseline data collected included clinical history and self-reported demographics, comorbidities, and HRQoL. TIBI-CaP scores were analyzed based on correlation analysis and analysis of variance (ANOVA). Estimated correlations were used to verify the association of TIBI-CaP scores to scores on the SF-12v2 and FACT-P questionnaires. ANOVA models were run with SF-12v2 and FACT-P as r...